"The Patagonia R1 Air Full-Zip Hoodie is built for the aerobic middle of a day out: the sustained climb, the long approach, the pitch where stopping to shed a layer costs time and warmth. It packs light enough to carry as a backup layer and performs well enough to be the primary one. The hood and slim cut work together so it moves with the body and stays put under a shell. What Our Gearhead® Experts Are Saying:""I wear this on the skintrack and keep it on through the first few hundred feet of climbing because the hollow-core yarns move sweat off fast enough that I never have to stop to strip a layer."""